On the drying potential of cavity ventilation behind brick veneer cladding: A detailed field study

Publication date: October 2017
Source:Building and Environment, Volume 123
Author(s): Michiel Vanpachtenbeke, Jelle Langmans, Jan Van den Bulcke, Joris Van Acker, Staf Roels
A qualitative and durable built environment requires an effective moisture control strategy. Moisture related problems can have an impact on the health of inhabitants or even jeopardize the building's structural integrity. Knowledge of the hygrothermal response and the drying potential of the current building enclosures under environmental loads is therefore crucial. In the current study detailed field experiments have been conducted in Belgium to study cavity ventilation behind brick veneer cladding. A simplified version of a South-West oriented cavity wall finished with brick veneer cladding has been analysed regarding the airflow pattern inside the cavity and the cavity's hygrothermal conditions. In this way, the drying potential of cavity ventilation behind brick veneer cladding can be assessed. For the dataset considered in the present article, the study showed that buoyancy induced cavity ventilation leads to a higher effective air change rate compared to cavity ventilation due to wind pressure. Furthermore, it was found that cavity ventilation is not of great help to dry out the whole outer leaf. However, it proved to lower the moisture levels inside the cavity, which – if e.g. the brick veneer is combined with a wooden loadbearing wall – might be important to avoid mould growth problems. The study also showed that climatic conditions play an important role in the drying potential: sunny but windless days have larger drying potential than cloudy but windy days.